270 Drs. Lochhead and Cramer. Gilycogenic Changes [Jan. 1, 
In every case glycogen was present, though in the earlier stages the 
amounts were extremely small. Thus, at the 18th day no quantitative 
estimation was attempted, but the iodine reaction was positive, and the 
extract, after inversion with acid, reduced a small amount of Fehling’s 
solution. Up to the 21st or 22nd day the amounts present were too small 
for accurate quantitative estimation, but the results are in all cases approxi- 
mate. It is interesting to note that glycogen cannot be demonstrated 
histochemically in the foetal liver before the 22nd day, and the percentage 
then is about 0:1. 
Up to the 24th day the amount of glycogen is very small, and a comparison 
with Table V shows that the percentage is below that of the remainder of the | 
foetal body. fPfliiger also obtained very small amounts in the liver of early 
foetuses, and sometimes had to be content with the qualitative demonstration 
of glycogen by the iodine reaction, even in organs weighing a considerable 
number of grammes. At the same time he found the foetal muscles to 
possess appreciable amounts, and he seeks to explain this anomaly by the 
imperfect feeding of the mother animals (sheep) for some days before they 
are slaughtered. The same objection might also be urged against some 
analyses we made of early foetal livers of sheep which showed only traces of 
elycogen. But such an objection is inadmissible for our series of foetal 
rabbits, in which the pregnant animals were kept on full diet up to the time 
of death. We must conclude, therefore, that during the earlier stages of 
development the liver contains only traces of glycogen, and has not yet taken 
up its glycogenic function. 
After the 24th day the analyses show different results. At the 25th day 
the percentage of glycogen rises, for the first time, above that of the remainder 
of the fcetal body, and on each subsequent day there is a well-marked 
increase, till at the 29th day we find almost half of the total foetal glycogen 
stored in the liver. Hence, though glycogen is present as early as the 
18th day at least, a marked change takes place in the fcetal liver about the 
beginning of the last week of pregnancy. It is only then that the liver takes 
up its glycogenic function. This fact accounts for the conflicting results 
which have been obtained by various authors from isolated observations on 
the glycogen content of foetal livers.* 
The results in no case reached the percentages obtained in maternal livers, 
which varied between 4:1 and 7°4 per cent., while the highest figure obtained 
in a foetal liver was 3:4 per cent. An exceptionally low result was obtained 
in the case of the animal killed on the 26th day. This animal, however, 
was in an abnormal state; one foetus was dead and the others were smaller 
* See Demant, ‘ Zeitschrift fiir Physiolog. Chemie,’ vol. 11, 1887, p. 142. 
